Originally Posted by Phenom
I always read this and don't completely get it. Here's why..... All I've read, the difference between the 2500's and the 3500's is just in the rear suspension. So, with that in mind, wouldn't adding to the rear suspension effectively increase the payload you could carry? That's all the manufacturer is doing. Granted, the engineers and lawyers don't get to have any input if one adds bags.
I can see in the 1/2 ton category this being true. but in the 3/4 to 1 ton, it seems logical that adding to the suspension could increase your payload numbers.
The engineers (and, sorta, the lawyers) have the equipment and knowledge to determine what weight increase would result by adding either air bags or helper springs, etc. That means they have done whatever testing thing they do to determine the new weights. Those of us as consumers do not have access to those resources so all we can say is the modification resulted in some unknown amount of increase. It could be 500 pounds, or it could be 25 pounds. Since one does not know what the number is then in reality there is no increase in payload.
The only advantage I've seen to adding airbags is increased stability, especially in the ½ ton models. In the case of my ½ ton, the rear axle rating is 3.900 pounds. CAT scale without any load other than fuel, driver, one pax and normal stuff carried (but no trailer) shows an operating weight of 5,500 pounds and rear axle load of 2,520. The max weight for the truck is 6,900 pounds and the rear axle limit is 3,900.
Look closely at those numbers...if I add 1,400 pounds of cargo I reach the 6,900 pound limit. Since cargo is loaded mostly in the aft section of the truck then adding 1,400 pounds will overload the axle by 20 pounds. Now, I can add airbags or super-duper springs, etc., but nothing is going to change weight wise. I'm not going to take the time to look up all the data for ¾ ton trucks but I'm pretty sure there are a lot of models that will have similar results...just bigger numbers.
The OP is questioning what a GCVW vs actual combined weight ratio would be a good number. Adding airbags is adding some unknown extra amount to the final number, which in turn lowers the ratio percentage (unless the GCVW is restricted due to gear ratio, transmission capability, etc). Regardless...all they do is increase stability and give one a warm fuzzy feeling that things are better.